ToME: the Tales of Maj'Eyal

magic-device affects it, as well as the level upon which you find the junkart and the activation of the junkart, with lower levels resulting in a easier to activate junkart, and better powers having higher fail rate. I am not sure about the fail rates with respect to increasing your magic device sk...

Sorry if this is well-known, but what affects the success rate of these objects? Is it Magic-Device, Magic, or what? Is there any way to check the concrete success rate of these objects?